How To Reduce RF Noise In Your Audio Video System Using TRIBUTARIES® Interconnects

Noise is a fact of life. It is electromagnetic radiation and can come from many sources including fluorescent lighting, motors, cellular phones, computers, radio/television broadcasters, and natural sources such as the sun.

The design of shielding contained within interconnects can have a dramatic effect on their performance. Some examples of shields are featured below.

Serve/Spiral Shields

A twist of copper wire around the center conductor insulator, serve, or spiral shields can be made ultra-flexible. However, serve shields can open up when flexed , which compromises shield effectiveness. A spiral of wire obviously affects the inductance of the shield. Therefore, spiral shields are rare in video and are usually audio only. They are most commonly used in courtesy cables that are included with equipment.

Braid Shields

Braid shields are formed by spinning wires or groups of wires around a core. This slow and labor-intensive process makes braiding the most expensive single step of cable manufacturing. Single braid coverage of up to 95% can be realized with this method however. Since braids always have "holes" where the wires cross, 100% coverage is not possible with braid. Dual braid coverage can be up to 99% coverage.

TRIBUTARIES® SCV-C the only component video cables available that use two concentric 95% coverage braided shields

Braid shields are most effective at frequencies from 1,000 Hz to 50 MHz (NTSC TV is around 5 MHz, high definition televsion can go as high as 20 MHz). For those frequencies, the low resistance of a braid gives good coverage. Below 1,000 Hz there is no standard braid material which is effective. The wavelengths are so long, and the low frequency energy so pronounced, that the only effective shielding is solid steel conduit. At 60 Hz even steel conduit only gives 27 dB of noise reduction. At frequencies above 50 MHz, braid becomes "wavelength dependant" where the holes look larger and larger as the wavelength gets smaller and smaller. The effective coverage of a braid gets worse and worse as the frequencies go beyond 50 MHz, especially when compared to a foil shield which has no holes.

TRIBUTARIES® DCV-C  the only component video cables available that use two concentric 95% coverage braided shields

Foil Shields

Since foil shields lack the mass and low resistance of braid shields, they exhibit poor to average low-frequency performance. However, after 50 MHz, foil shields have excellent high frequency coverage. Since foil is a continuous sheet of metal, coverage can be 100%. Foil shields are typically used for satellite or cable TV applications.

Combination Shields

Combination shields consist of foil and braid combined. Due to their construction, combination cables are the most expensive to build. However, they give the best broadband coverage since they contain a braid for low frequencies and a foil for high frequencies. All TRIBUTARIES® interconnects use combination shields, even our inexpensive Alpha series cables. For the very best protection against radio frequency noise, use TRIBUTARIES® cables.